Input Delay Estimation for Input-Affine Dynamical Systems Based on Taylor Expansion

In this brief, we propose a novel method based on the Taylor expansion for the estimation of input delay for a class of input-affine dynamical systems. The proposed method guarantees the asymptotic convergence of the estimation error to zero. An application to the input delay estimation of a continuous stirred tank reactor system shows the effectiveness of the proposed method

Development of robust fuzzy control methods and their applications to a mechanical system

In this study, a non-singleton fuzzy sliding control based strategies are investigated with simulation and also experimental studies in order to minimize angular velocity ripples of the nonlinear four-bar mechanism when it is driven by an electric motor. The mathematical model of the full system included the motor and four-bar mechanism is first obtained and open loop reply of the system is illustrated to show angular velocity ripples of the crank in the presence of the constant potential source. Secondly, an optimized PID controller by using pattern search is designed to reduce crank angular velocity ripples for the closed loop system. A new non-singleton type-1 fuzzy sliding controller is designed in order to obtain stable crank angular velocity in the steady state and performances of different types of fuzzy sliding controllers are comparatively illustrated. In addition to simulation results, experimental results of the controlled systems are also presented in order to show the effectiveness of the controllers in practice. As far as the industrial applications are concerned, simpler and more practical control algorithm is obtained with non-singleton type-1 fuzzy sliding control structure.Bu çalışmada, bir elektrik motoruyla sürülen doğrusal olmayan dört-kol mekanizmasının açısal hız dalgalanmalarını minimuma indirgemek için non-singleton bulanık kayma kipli bir kontrol uygulaması benzetim ve deneysel çalışmalarla gerçekleştirilmiştir. Öncelikle, motor ve dört-kol mekanizmasını içeren bütün sistemin matematiksel modeli çıkarılmış ve sabit kaynak gerilimi uygulandığında krank açısal hızındaki dalgalanmaları göstermek için sistemin açık çevrim cevabı sunulmuştur. İkinci olarak, kapalı çevrim sistem için karank açısal hızındaki dalgalanmaları azaltacak bir optimum PID kontrolör gerçekleştirilmiştir. Kalıcı durumda krank açısal hızını sabitlemek için yeni bir non-singleton tip-1 bulanık kayma kipli kontrolör tasarlanmıştır ve farklı tip bulanık kayma kipli kontrolörlerin performansları karşılaştırılmalı olarak gösterilmiştir. Benzetim sonuçlarına ek olarak pratikte önerilen kontrolörlerin etkinliğini göstermek için kontrol edilen sistemlerin deneysel sonuçları da sunulmuştur. Endüstriyel uygulamalar göz önünde bulundurulduğunda, non-singleton tip-1 bulanık kayma kipli kontrol yapısının daha basit ve pratik olduğu sonucuna varılmıştı

Adaptive fuzzy tracking control for a class of uncertain MIMO nonlinear systems using disturbance observer

In this paper, the adaptive fuzzy tracking control is proposed for a class of multi-input and multioutput (MIMO) nonlinear systems in the presence of system uncertainties, unknown non-symmetric input saturation and external disturbances. Fuzzy logic systems (FLS) are used to approximate the system uncertainty of MIMO nonlinear systems. Then, the compound disturbance containing the approximation error and the time-varying external disturbance that cannot be directly measured are estimated via a disturbance observer. By appropriately choosing the gain matrix, the disturbance observer can approximate the compound disturbance well and the estimate error converges to a compact set. This control strategy is further extended to develop adaptive fuzzy tracking control for MIMO nonlinear systems by coping with practical issues in engineering applications, in particular unknown non-symmetric input saturation and control singularity. Within this setting, the disturbance observer technique is combined with the FLS approximation technique to compensate for the effects of unknown input saturation and control singularity. Lyapunov approach based analysis shows that semi-global uniform boundedness of the closed-loop signals is guaranteed under the proposed tracking control techniques. Numerical simulation results are presented to illustrate the effectiveness of the proposed tracking control schemes

Robust fault tolerant control of induction motor system

Research into fault tolerant control (FTC, a set of techniques that are developed to increase plant availability and reduce the risk of safety hazards) for induction motors is motivated by practical concerns including the need for enhanced reliability, improved maintenance operations and reduced cost. Its aim is to prevent that simple faults develop into serious failure. Although, the subject of induction motor control is well known, the main topics in the literature are concerned with scalar and vector control and structural stability. However, induction machines experience various fault scenarios and to meet the above requirements FTC strategies based on existing or more advanced control methods become desirable. Some earlier studies on FTC have addressed particular problems of 3-phase sensor current/voltage FTC, torque FTC, etc. However, the development of these methods lacks a more general understanding of the overall problem of FTC for an induction motor based on a true fault classification of possible fault types.In order to develop a more general approach to FTC for induction motors, i.e. not just designing specific control approaches for individual induction motor fault scenarios, this thesis has carried out a systematic research on induction motor systems considering the various faults that can typically be present, having either “additive” fault or “multiplicative” effects on the system dynamics, according to whether the faults are sensor or actuator (additive fault) types or component or motor faults (multiplicative fault) types.To achieve the required objectives, an active approach to FTC is used, making use of fault estimation (FE, an approach that determine the magnitude of a fault signal online) and fault compensation. This approach of FTC/FE considers an integration of the electrical and mechanical dynamics, initially using adaptive and/or sliding mode observers, Linear Parameter Varying (LPV, in which nonlinear systems are locally decomposed into several linear systems scheduled by varying parameters) and then using back-stepping control combined with observer/estimation methods for handling certain forms of nonlinearity.In conclusion, the thesis proposed an integrated research of induction motor FTC/FE with the consideration of different types of faults and different types of uncertainties, and validated the approaches through simulations and experiments

Evaluation of a Multi-Variable Self-Learning Fuzzy Logic Controller

In spite of the usefulness of fuzzy control, its main drawback comes from lack of a systematic control design methodology. The most challenging aspect of the design of a fuzzy logic controller is the elicitation of the control rules for its rule base. In this paper, a scheme capable of elicitation of acceptable rules for multivariable fuzzy logic controllers is derived by extending an algorithm that enables a single-input-single-output fuzzy logic controller to self-learn its rule-base. The performance of the proposed self-learning procedure is investigated and evaluated by means of simulation studies of a hypothetical plant. The results obtained indicate that the approach could be effective in the control of nonlinear multivariable industrial processes

Recent Advances in Robust Control

Robust control has been a topic of active research in the last three decades culminating in H_2/H_\infty and \mu design methods followed by research on parametric robustness, initially motivated by Kharitonov's theorem, the extension to non-linear time delay systems, and other more recent methods. The two volumes of Recent Advances in Robust Control give a selective overview of recent theoretical developments and present selected application examples. The volumes comprise 39 contributions covering various theoretical aspects as well as different application areas. The first volume covers selected problems in the theory of robust control and its application to robotic and electromechanical systems. The second volume is dedicated to special topics in robust control and problem specific solutions. Recent Advances in Robust Control will be a valuable reference for those interested in the recent theoretical advances and for researchers working in the broad field of robotics and mechatronics

Hybrid intelligent machine systems : design, modeling and control

To further improve performances of machine systems, mechatronics offers some opportunities. Traditionally, mechatronics deals with how to integrate mechanics and electronics without a systematic approach. This thesis generalizes the concept of mechatronics into a new concept called hybrid intelligent machine system. A hybrid intelligent machine system is a system where two or more elements combine to play at least one of the roles such as sensor, actuator, or control mechanism, and contribute to the system behaviour. The common feature with the hybrid intelligent machine system is thus the presence of two or more entities responsible for the system behaviour with each having its different strength complementary to the others. The hybrid intelligent machine system is further viewed from the system’s structure, behaviour, function, and principle, which has led to the distinction of (1) the hybrid actuation system, (2) the hybrid motion system (mechanism), and (3) the hybrid control system. This thesis describes a comprehensive study on three hybrid intelligent machine systems. In the case of the hybrid actuation system, the study has developed a control method for the “true” hybrid actuation configuration in which the constant velocity motor is not “mimicked” by the servomotor which is treated in literature. In the case of the hybrid motion system, the study has resulted in a novel mechanism structure based on the compliant mechanism which allows the micro- and macro-motions to be integrated within a common framework. It should be noted that the existing designs in literature all take a serial structure for micro- and macro-motions. In the case of hybrid control system, a novel family of control laws is developed, which is primarily based on the iterative learning of the previous driving torque (as a feedforward part) and various feedback control laws. This new family of control laws is rooted in the computer-torque-control (CTC) law with an off-line learned torque in replacement of an analytically formulated torque in the forward part of the CTC law. This thesis also presents the verification of these novel developments by both simulation and experiments. Simulation studies are presented for the hybrid actuation system and the hybrid motion system while experimental studies are carried out for the hybrid control system

Fault tolerant control for nonlinear aircraft based on feedback linearization

The thesis concerns the fault tolerant flight control (FTFC) problem for nonlinear aircraft by making use of analytical redundancy. Considering initially fault-free flight, the feedback linearization theory plays an important role to provide a baseline control approach for de-coupling and stabilizing a non-linear statically unstable aircraft system. Then several reconfigurable control strategies are studied to provide further robust control performance:- A neural network (NN)-based adaption mechanism is used to develop reconfigurable FTFC performance through the combination of a concurrent updated learninglaw. - The combined feedback linearization and NN adaptor FTFC system is further improved through the use of a sliding mode control (SMC) strategy to enhance the convergence of the NN learning adaptor. - An approach to simultaneous estimation of both state and fault signals is incorporated within an active FTFC system.The faults acting independently on the three primary actuators of the nonlinear aircraft are compensated in the control system.The theoretical ideas developed in the thesis have been applied to the nonlinear Machan Unmanned Aerial Vehicle (UAV) system. The simulation results obtained from a tracking control system demonstrate the improved fault tolerant performance for all the presented control schemes, validated under various faults and disturbance scenarios.A Boeing 747 nonlinear benchmark model, developed within the framework of the GARTEUR FM-AG 16 project “fault tolerant flight control systems”,is used for the purpose of further simulation study and testing of the FTFC scheme developed by making the combined use of concurrent learning NN and SMC theory. The simulation results under the given fault scenario show a promising reconfiguration performance